class Solution {
public:
    int maxProfit(vector<int>& prices) {
        vector<vector<int> > dp(prices.size(),vector<int>(4,0));
        dp[0][0] = -prices[0];
        for(int i = 1;i < prices.size();i++){
            dp[i][0] = max(dp[i-1][0],max(dp[i-1][3],dp[i-1][2])-prices[i]);
            dp[i][1] = dp[i-1][0]+prices[i];
            dp[i][2] = max(dp[i-1][3],dp[i-1][2]);
            dp[i][3] = dp[i-1][1];
        }
        return max(dp[prices.size()-1][1],max(dp[prices.size()-1][2],dp[prices.size()-1][3]));
    }
};
